Keller kills Winthrop as revenge for Winthrop killing Beecher's father. When Beecher gets paroled and offers to help Keller's case, Keller pretends to be happy but makes a plan for he and Beecher to be together in Oz as he knows he's never going to get out. He convinces Beecher to make a delivery on the outside for him but, its a set up and Beecher gets arrested and returned to Oz. Beecher eventually discovers Keller's part in this and tells him they are through. Keller's trickery knows no end as he switches props during the Oz production of Hamlet so Beecher gets a real shank and not the prop one. When Beecher goes to stab Schillinger, the knife wound goes deep and kills Schillinger on the spot. Beecher eventually adds all this up and tells Keller to leave him alone, although Keller explains that he did these things so he and Beecher would be together forever. Beecher refuses and during the argument, pushes Keller away from him, causing Keller to fall backwards over the rail and break his neck, which kills him.
Returns to Oz as part of a deal to get him to trial for one of his past murders. This of course gives Beecher hope, although Keller seems more indifferent. While his trial looms, Keller's placed in protective custody. While in protective custody, Officer Howell decides to "sample" Keller's goods. Keller's a willing participant for a while but soon tires of her. When he refuses her, she beats him severely and lies to make it appear as if he attacked her. Once Keller recuperates from the beating, his trial comes up and he's convicted on an old murder rap. He's them moved to death row after guilty verdict is handed down. Beecher comes to see him and in a passionate moment, they kiss...deeply.
Season 4 Part 2
An old running buddy of Keller's arrives to Oz and Keller takes up with him to make Beecher jealous. Although Keller and Beecher do still love each other, they're not together and Beecher begins having sex with other inmates to get back at Keller. Anyway, Keller's buddy Ronnie, is not as sincere as he presents himself and is really working with the feds to get Keller on past murder charges. Beecher warns Keller about this. Keller dismisses him but is honestly suspicious so what does he do? While Ronnie's performing fellatio on Keller, Keller reaches down and snaps Ronnie's neck, killing him instantly. In an act of ultimate sacrifice, Keller confesses to Hank Schillinger's murder so Schillinger won't seek revenge on Beecher. Because of this, Keller get's transferred to another prison, leaving Beecher heartbroken.
Season 4 Part 1
Keller got shot by another inmate. Then, Beecher accused him of planning the death of his son (which wasn't true). Beecher soon tries to apologize but Keller rebukes him and gets moved to another pod. After his shooting, Keller decides to find spiritual solace and forgiveness only Father Mukada refuses to absolve him of heinous murders he performed in the past. Keller then seeks refuge with Sister Pete only she rebukes him. She still doesn't trust him after he tried to use her to get to Beecher last season. Keller soon discovers that Eli Rabitz gave Beecher the lie about Keller killing Beecher's son. Keller lets Rabitz know that he will kill him only he doesn't say when. When Keller finally does go to kill Eli, Robson is there, also to kill Eli. Eli suffers a fatal heart attack and dies on the spot, denying Keller or Robson the kill. Keller then hooks up with O'Reily to plan Querns' demise after Querns begins transferring white prisoners out of Oz while bringing more black inmates in. The plan involves two high profile killings to draw investigations into Querns' mishandling of Oz. Once Keller kills both Shemin and Mondo Browne, he and O'Reily settle in and wait for the consequences.
Keller realizes that he really does love Beecher, so he decides to try and win Beecher back. Beecher tells Keller the road to redemption with him begins with Keller fully confessing to McManus his part in Beecher's beating. Even though Keller does confess, Beecher's not impressed, making Keller even more confused.Furthermore, Keller gets shanked by a mysterious attacker. After recovering from his wounds, he starts attending sessions with Sister Pete to seemingly get to the bottom of his issues. Keller's secret plan is to get Sister Pete to influence Beecher into returning to him. Once Sister Pete realizes this, she turns her back on Keller, never trusting him again. Keller does get his chance with Beecher after a fight in the gym results in Beecher getting stabbed by Schillinger, and Keller coming to his aid. As OZ goes on lockdown, Beecher and Keller are "reunited" in their pod.
Keller arrives at OZ on a secret mission to win Beecher's trust. Beecher is hesitant at first but soon gets close to Keller. He shares intimate stories and fears with Keller who responds by comforting and defending him against other Aryans. When Beecher arrives at the gym for a workout with Keller, he GETS one from Keller -- and Schillinger (Keller's old buddy!), who joins with Keller to deliver a brutal beating resulting in Beecher's legs and arms getting broken.